Topological thermal Hall effect and nondissipative transport of the nanometric skyrmion lattice in Gd2PdSi3

Abstract We report the first observation of a topological thermal Hall effect (tTHE) of electrons moving through a magnetic skyrmion lattice (SkL) of short period, where the skyrmion diameter is only a few nanometers. In the hexagonal intermetallic Gd2PdSi3, we observe a characteristic anomaly in the magnetic field dependence of the thermal Hall conductivity κxy, which scales well with the anomaly in the electrical Hall conductivity σxy and is closely related to the topological winding number of the SkL ground state. The relative magnitude of entropy and charge currents, defined as the Lorenz ratio ∼κxy/(σxyT), is consistent with a nondissipative, or intrinsic, mechanism for the topological Hall effect. We stress that the Berry phase in momentum space (k-space) causes such a nondissipative Hall transport, independent of the carrier relaxation time.